LEDs are core components of LED lamps. LEDs have been widely used in various areas in accord with the rapid development of the LED technology. The demand of high power has caused the size of LED chips to become larger. However, large LED chips have poor current spreading effect, and therefore requiring structure optimization. At present, the conventional large size LEDs have adopted the structure of multi-electrode extension, so that the current can spread throughout the large LED chips.
FIG. 1 is the top view of a GaN-based LED adopting the structure of multi-electrode extension. As shown in FIG. 1, either a first electrode or a second electrode of the LED comprises electrode contact points (11, 21) and a plurality of extended electrodes (12, 22). The extended electrodes of the first electrode and the extended electrodes of the second electrode are arranged in an interlaced arrangement.
FIG. 2 is the cross-sectional view along line AA of the LED device in FIG. 1. As shown in FIG. 2, reference 10 indicates the first electrode, reference 13 indicates an insulating structure, reference 20 indicates a second electrode, reference 30 indicates a substrate, reference 40 indicates a buffer layer, reference 50 indicates an unintentional doped layer, reference 60 indicates a first conductive layer, reference 70 indicates an active layer, reference 80 indicates a second conductive layer, and reference 90 indicates a transparent conductive layer. Referring to FIG. 2, the extended electrode of the first electrode 10, through the epitaxial structure of the LED, extends to the first conductive layer 60, and therefore allowing the extended electrode of the first electrode 10 to electrically contact the first conductive layer 60. The insulating structure 13 is attached in the sidewall of the extended electrode of the first electrode 10, preventing the sidewall of the extended electrode of the first electrode from contacting the epitaxial structure.
FIG. 3 is the schematic view of the current extension of the LED device in FIG. 2. For the LED with same-side electrode structure, the current easily gets crowded in the region of dashed box indicated in FIG. 3 when the extended electrode of the first electrode 10 carries large current, and therefore reducing the current spreading effect.